This Core operates as a service, a developmental laboratory, and a resource for the Program Project. Both the overall objectives and the specific aims of the Core laboratories follow primarily from those of the individual projects; e.g., development of methods for identification or quantitation of carcinogen-nucleic acid adducts, carcinogen-protein adducts, and carcinogen metabolites and/or their conjugates. This includes continued evaluation of capillary HPLC-LIF for quantitation of protein or DNA damage and continued development of capillary HPLC and nanoelectrospray/microelectrospray tandem MS techniques to characterize and quantitate modified proteins or DNA. Development or adaptation of methods to quantitate DNA or protein adducts or urinary levels of PhIP or 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) or their metabolites during previous funding periods, for example, was in direct response to the needs of epidemiological studies that evolved into Project 1 in this proposal. Many of the methods listed below were adapted or developed by the Core in this context and some methods, such as quantitation of aromatic amine-hemoglobin adducts by NICI GC-MS have in some cases become the methods of choice for other laboratories that carry out related investigations. The specific aims of the various research projects involve quantitation in urine, physiological fluids or tissue, of DNA and protein adducts of several carcinogens including aflatoxin and aromatic amines and related compounds (e.g., alkylated anilines) and quantitation of urinary excretion of the food-related carcinogen, PhIP, and its metabolites or conjugates. Literature methods are often based on pure or in vitro samples, so methods are developed for the isolation or concentration of low levels of these compounds in complex biological mixtures using, for example, solid-phase extractions or affinity chromatography. Where necessary, for example with tandem MS methods for analyses of modified oligonucleotides, the developmental work is done in the Core laboratories. Specific objectives for additional analyses or techniques include: (1) development and applications of ultrasensitive MS methods for nucleobase and deoxyribonucleoside adducts; (2) development and applications of HPLC-LIF methods for quantitation of derivatized adducts; and (3) transfer of HPLC-LIF technology to the Johns Hopkins University (Project 1 and Core).